#pragma once


struct perlin
{
	int p[512];
	perlin(void);
	static perlin & getInstance(){static perlin instance; return
		instance;}

	static float debugMaxPer;
	static float debugMinPer;
};

static int
	permutation[] = { 151,160,137,91,90,15,
	131,13,201,95,96,53,194,233,7,225,140,36,103,30,69,142,8,99,37,240,21,10,23,
	190,6,148,247,120,234,75,0,26,197,62,94,252,219,203,117,35,11,32,57,177,33,
	88,237,149,56,87,174,20,125,136,171,168,68,175,74,165,71,134,139,48,27,166,
	77,146,158,231,83,111,229,122,60,211,133,230,220,105,92,41,55,46,245,40,244,
	102,143,54, 65,25,63,161, 1,216,80,73,209,76,132,187,208,89,18,169,200,196,
	135,130,116,188,159,86,164,100,109,198,173,186,3,64,52,217,226,250,124,123,
	5,202,38,147,118,126,255,82,85,212,207,206,59,227,47,16,58,17,182,189,28,42,
	23,183,170,213,119,248,152, 2,44,154,163, 70,221,153,101,155,167,43,172,9,
	129,22,39,253,19,98,108,110,79,113,224,232,178,185, 112,104,218,246,97,228,
	251,34,242,193,238,210,144,12,191,179,162,241,81,51,145,235,249,14,239,107,
	49,192,214, 31,181,199,106,157,184, 84,204,176,115,121,50,45,127,4,150,254,
	138,236,205,93,222,114,67,29,24,72,243,141,128,195,78,66,215,61,156,180
};

static float fade(float t)
{ 
	return t * t * t * (t * (t * 6 - 15) + 10);
}

static float lerp(float t, float a, float b) { 
	return a + t * (b - a);
}

static double grad(int hash, double x, double y, double z) {
	int h = hash & 15;
	// CONVERT LO 4 BITS OF HASH CODE
	double u = h<8||h==12||h==13 ? x : y, // INTO 12 GRADIENT DIRECTIONS.
		v = h < 4||h == 12||h == 13 ? y : z;
	return ((h & 1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
}

float noise(float x, float y, float z);